Roll out formwork support

ABSTRACT

An adjustable support for shoring and rolling out formwork intact for reuse in pouring concrete slabs for successively higher floors in which a sleeve screw telescopes freely in a tubular support mounted on a structural column and is threadably supported by a non-rotatable nut resting loosely on the tube with a winged nut above it. The upper ends of the sleeve screw rotatively telescope with each other, one having a spindle received internally in the sleeve screw end and the other a collar received around the sleeve screw as adjustably supported by the winged nut to vary the relative heights of the roller and shoe. The sleeve screw is rotatable by a hand or power wrench from below the tubular support to adjust the roller and shoe vertically as a unit.

[111 7 3,815,858 June 11, 1974 United States Patent 91 Mocny et al.

[ ROLL OUT FORMWORK SUPPORT [75] Inventors: Richard C. Mocny, Prospect Heights; Francis B. Mueller, Primary Exam ner-J. Franklin Foss Downers Grove, both of I11.

[73] Assignee: Waco Scaffold & Shoring Co.,

[57] ABSTRACT An adjustable support for shoring and rolling out Division of Bliss & Laughlin formwork intact for reuse in pouring concrete slabs Industries, Inc., Schiller Park, 111.

Jan. 12, 1973 Appl. No.: 322,969

for successively higher floors in which a sleeve screw Filed: telescopes freely in a tubular support mounted on a structural column and is threadably supported by a non-rotatable nut resting loosely on the tube with a winged nut above it. The upper ends of the sleeve screw rotatively telescope with each other, one having a spindle received internally in the sleeve screw end and the other a collar received around the sleeve 22 screw as adjustably supported by the winged nut to [52] US. 248/295, 249/219 R [51] Int. Cl..... A47f 5/10, A47h 33/00, E04g 17/16 [58] Field of Search..... 248/205 R, 295; 249/219 R,

vary the relative heights of the roller and shoe. The

[56] Ref ren Cit d sleeve screw is rotatable by a hand or power wrench UNITED STATES PATENTS from below the tubular support to adjust the roller and shoe vertically as a unit.

10 Claims, 8 Drawing Figures 2,386,525 10/1945 249/18 UX 3 504,879 4/1970 Strickland................... 249/219 R X ROLL OUT FORMWORK SUPPORT CROSS REFERENCE Co-filed applications of Lane, Ser. No. 264,277 new Pat. No. 3,797,794for Roll Out Form Support; and Moritz et al., Ser. No. 264,274 now Pat. No.

3,797,793 for Shoring Scaffold and Formwork Support. 7

BACKGROUND OF THE INVENTION Wherever formwork is to be supported for the pouring of concrete floor slabs, adjustments at the top or bottom of many supports have to be. made for vertical or horizontal positioning with or without relative movement in one or more directions. Either the footing or vertical location for each support member on columns has to be accommodatedwith respect to the others, or the position of the formwork must be adjusted both vertically and horizontally for coordination. It would be of great convenience to make directional as well as vertical adjustments with both rolling.and rigid members engageable with the framework to hold or move a unitary supported load at each support station into proper orientation.

Furthermore, work scaffolds and formwork are generally moved intact from place to place to perform their functions and it is desiredfor repeated uses, to roll one or the other of them intact between work positions and there rigidly support them at adjusted heights or inclinations.

Although reusable formwork support brackets mounted on the structural columns of a buildingunder construction have been usedheretofore which involve lowering formwork a short distance onto fixed bracket rollers so that the framework can be removed intact and re-used for other sections of flooring, the working space for handling and adjustingthe formwork position is limited, particularly if a bracket itself is also to hold the formwork rigidly in place during slab pouring operations. Difficulties in mounting, adjusting, servicing and removing the brackets and formwork cause delay and also the lack of space inhibits-the use of unitary multi-level fonns.

Moreover, removable formwork support structures which have brackets that include formwork roll-out rollers rigidly oriented: directionally and rotatable heads horizontally spaced therefrom required thestrict positioning of mounting bolts sleeves vertically and laterally in both square and round columns when the columns are being poured. to support the next floor slab.

Furthermore, due to high location of supports and the adjustment for rigidity, special tools are required, female threads are fouled and male threads are difficult to clear of damaging corrosive cement. Furthermore, a non-adjustable roll-out level incurs interference and other difficulties that may arise which involve alteration or damage to the formwork in clearing and moving it.

Heretofore, due to theirhigh location and limited clearance relationship, adjustable. jack screw mechanisms that are mechanically integrated as a part of the whole supportassembly provide a total weight that must be manually handled when'securing. and removing it from its high support position;

SUMMARY O'FTHE INVENTION In the present inventionthe support is asimple frame fabricated by welding, or a steel casting, and having a vertically oriented tubular element which closely but freely receives an externally square-threaded tubular sleeve member of a screw assembly in axial telescoping relationship for rigid erectness. Two nuts are carried by the sleeve screw. The lower nut non-rotatably engages the support in weight bearing relation for vertical adjustments by rotating thesleeve screw from its lower end. The upper nut is a winged nut.

The upper end of the screw rotatably supports a roller fixture and also a load bearing head fixture. They non-rotatively telescope with each other as adjusted by the winged nut to their weight bearing positions. The relative adjustment between the roller fixture and head is not changed when they are moved vertically as a unit by sleeve screw rotation. Thereby the roller and shoe jointly have universal directional orientation as well as a separate vertical adjustment with respect to each other. The roller fixture, the head fixture and the sleeve screw can be lifted from their respective supported positions separately or collectively for repair, shipment and replacement.

The support can be installed or removed without the screw assembly beingpresent and the screw assembly can be installed or removed easily by axial telescopic movement vertically, or horizontally, to or from its working position after the support has been lifted and is being secured in place. Also, the wing nut can be grossly adjusted before the screw assembly is installed. Therefore a workman merely finalizes the major adjustment with an extension wrench from below the support with substantial savings of time and effort.

Another object and advantage of the invention is the ready interchangeability and adjustment of self contained screw assemblies of different lengths for special applications. Additionally, the invention can be used with other vertically disposed tubular supports secured to structural columns or independently standing shoring membersthatmight be required between columns having a widespan.

Other and further objects and advantages will become apparent from the. description and drawings which follow including..the.ease of fabrication of the embodiments shown; simplicity of operation and ser vicing; and, minimized effort to adjust relative positions of parts with minimum friction.

IN THE DRAWINGS FIG. 1 is an upwardly directed perspective view showingone of theembodiments of the invention operatingto support formwork for a poured concrete floor slab;

FIG. 2 is a perspective view of the support shown in FIG. 1 in an intermediate stageof assembly;

FIG. 3 isa vertical sectional view of the assembled support shown in FIG. 1;.

FIG. 4 is a cross-sectional view of the assembly shown in FIG. 1 taken'on line.44 of FIG. 3;

FIGS. 5 and 6 are fragmentary, partly sectional views showing parts of the embodiment in FIG. 1 in alternate operational positions;

FIG. 7 is a viewsimilar to FIG. 3. showing a modified form thereof;

FIG. 8 is a perspective .view of a vertical shoring tube, not bolted to a column, in which the jack screw is received at the top to adjustably support formwork between widely spaced columns.

THE PREFERRED EMBODIMENTS Referring in further detail to the drawings, a concrete structural column 10, of a building that is being built of poured concrete, is shown in FIG. 1 supporting formwork 12 upon which concrete is poured to form the slab 14 of the next upper floor. After hardening, another series of structural columns will be formed on the slab 14 as extensions of the others and the formwork illustrated can be lowered a substantial distance and rolled out intact in a horizontal direction, and then rigidly relocated on'the new columns for reuse in forming the next slab above slab l4, etcl Although the frame of the formwork may include I beams, timbers 16 are shown by way of simple illustration which support plywood form panels 18. The column is one of many that are spaced and aligned in parallel rows in a repetitive pattern with each having spaced horizontal tubular elements 20 embedded in them to receive removable bolts or studs 22 therethrough that accept nuts 26 thereon to clamp the frame portion 23 of the support 24 in place. The support includes the tube 32 to receive and support the screw assembly 25, upon which the-formwork is removably supported at adjustable heights.

Although the support 24 can be made as a single steel casting without need for extensive machining, it is shown as comprising a section of a channel beam 27 with mounting tubes 28 extending through the flanges 39 thereof and across the web portion 34 as welded thereto. The tubes receive the mounting studs or bolts 22 that clamp the support removably to the column by the use of nuts 26. Spaced right triangular braces 36 are welded on the opposite side of the web 34 to secure the tube 32 rigidly in place along one edge of the channel beam section with the ends 33 of the tube preferably terminating a substantial distance inwardly from opposite ends of the channel beam section. The support 24 may be secured by the nuts 26 and bolts 22 with either end of the channel beam 27 up, and the flanges 39 and braces 36 can serve as gripping elements or handles during installation, adjustment and removal. Generally only two bolts are required.

The nuts 26 on the bolts 22, when tightened, clamp the flange 39 that is remote from the tube 32 flat against the column preferably at a height well below the position of the framework to provide an easy working space and a substantial roll-out drop. As later discussed, the screw assembly can be slipped into place during the applications of the two bolts and nuts as when the tube is momentarily disposed horizontally with one bolt in place. For this purpose the tube 32 has an opening 40 (FIG. 4) therethrough and telescopically receives therein the lower end 31 of the screw 42 of the screw assembly. The screw may have external longitudinal undulations thereon such as a rack, or preferably a square coarse helical thread 41 such as a modified four pitch Acme, although shown for simplicity in the drawings as a V-thread, for rotative vertical load bearing and adjustment and carries two nuts 38 and 58 above the tube 32. Preferably the screw 42 is a sleeve more than twice the length of the tube '32 with the thread 41 ending, or obstructed, at a point 46 spaced from its lower end a distance substantially equal to the length of the tube 32 leaving the lower end of the screw 42 preferably smooth as at 43 to fit with the tube and also to substantially reduce thread contamination from the bottom of the tube. The sleeve screw is preferably provided at its lower end with a wrenching member. It can be machined or formed square, or a cast member can be used but is illustrated as a hex head 30 nut welded thereto at 35 for engagement by a crank or power wrench (not shown) for rotating it. The opening 37 through the nut drains the interior of the sleeve screw 42 to avoid dangers of water collection and freeze ups.

The upper end of the sleeve screw 42 removably supports two fixtures rotatively which telescope with each other and the sleeve screw. The sleeve screw 42 internally receives the vertical spindle 47 of a roller fixture 48 that has a yoke 50 secured therto whose arms 51 carry an axle 52 that journals the roller 54. The bight of the yoke 50 rests rotatively on the flattened upper end 55 of the sleeve screw.

The other fixture 56 is load bearing and has a depending collar 57 received externally on the upper end of the sleeve screw 42 as rotatively and adjustably supported-in axial telescoping relationship by the winged nut 58 threaded on the sleeve screw adjacent to its upper end. The collar 57 carries a yoke 60 telescoping laterally over the roller fixture 48 and terminating in diverging flat arms 63 that define a flat head 62 to engage a beam of the formwork 12. The edges of the yoke 60 are reinforced by contour cut plates 61 welded thereto and defining a well 65 into which the roller fixture can non-rotatively telescope to a level below the head 62.

Vertical ears or pins 64 provided upon the head receive the formwork beam 16 between them for geometric alignment and the beam in turn thereby nonrotatively supports the head fixture 56 and roller fixture 48 against rotation relative to the support 24. This non-rotative engagement of the pins 64 with the beam also prevents rotation of both the head 60 and the roller 54 on the top of the screw regardless of which one is actually in contact with the beam 16. The relative support adjustment between the head 62 and roller 54 is not disturbed when bodily raising and lowering the two fixtures as a unit when turning the screw 42 in the cam nut 38 for gross or fine adjustment levels.

Thus, the roller and head fixtures are rotatable on top of the screw 41 for universal directional orientation in a horizontal plane to engage a formwork beam so oriented. Adjustment of the winged nut 58 on the sleeve screw 42 raises or lowers one fixture with respect to the other without relative rotation between them and the screw 42 bodily raises and lowers them as a unit in any adjusted relation by being rotated in the non-rotative nut 38. Accordingly, the roller is freely orientable to accommodate the direction of endwise movement of the beam, and also be readily repaired if damage is in curred. Either the roller or head, or both, can be removed and replaced by merely lifting either or both members from the upper end of the screw sleeve.

The lower nut 38 on the sleeve screw 42, as mentioned, is non-rotatably supported when the sleeve screw rests in place on the top 67 of the tube 32. As noted, the tube 32 is shorter than the web portion 34 of the channel beam 37, preferably at both ends 33, by a distance approximately the height of the nut 38 and the space between the web 27 and the exterior surface of the screw 42 is less than the major diameter of the hex wrenching contour of the nut 38. Thereby, when the screw jack assembly is lowered into place any minordiameter flat portion 68 of the hex contour of the nut 38 will be disposed next to the web 27 (FIG. 4) and will be thereby held against rotation when the nut 38 is in weight bearing relation on the tube 32.

With the nut 38 resting on the tube 32, whichever end is up, the load of the formwork beam 16 is carried by the nut 38 from the screw sleeve 42 regardless of which fixture is the highest. If the roller 54 is highest the load is transmitted directly from the roller fixture 48 to the upper end of the sleeve screw. If the head 62 is the highest, the load is transmitted by the head fixture 56 through the winged nut 58, to the sleeve screw 42 and nut 38.

With the present invention the relative installtion heights of the respective supports 24 are not critically significant regarding variations in heights between respective sets of mounting bolts 22 since the roller and head assembly units can be leveled easily throughout the building area by a crank or power wrench (not shown) engaging the hex headed lower ends 30 of the sleeve screws and adjusted, if need be, to transit sightings. Thereby all fixture units can be leveled not only for pouring the concrete floor slab but also for formwork roll out.

The formwork is generally lowered intact onto screw assemblies that have been inspected and adjusted to a desired gross level. However, there are occasions while supporting formwork beams that a screw assembly has to be serviced, or replaced, and then readjusted. For these occasions a modification 62A (FIG. 7) of the head 62 comprises locating pins 64A at the corners of the head 62A. And, depending on the direction of rotation of the screw 42 that raises them, preferably at least one of these pins 64AT is higher than the other by as much as one half of the lead of the thread 41 on a trailing corner. Thereby the head 62A and roller 54 are disposed properly under and in alignment with the beam since the higher trailing pins or pins 64AT are first to engage the leading side or sides of the beam as the head rises in a helical path 66 when rotating with the screw that is being advanced by its turning during height readjustment.

In use, once the forms are removed from poured concrete columns exposing the vertically spaced tubes 28 embedded in them, the support 24 for each column is easily lifted and one bolt 22 is inserted and its nut 26 is partially tightened, preferably the upper one, and the support 24 and its tube 32 are temporarily tilted to extend horizontally. In this position the sleeve screws 42 with the two nuts 38 and 58 on them can be easily inserted in the tube 32. The support 24 and its tubes 32 are then oriented vertically and the other bolts 22 attached and both nuts 38 tightened. Thereafter the head fixtures 56 and roller fixtures 48 are dropped into their working positions in that order, or as units, on the upper end of the screw 42 with the heads 62 slightly higher than the rollers 54. The heads 62 can later be brought to a predetermined level by turning the sleeve screw 42 by its hex head 30 from below the support to align the heads 56. The formwork beams 16 can then be placed on the heads 62 and the final height and leveling made by screw adjustment with the formwork in place for pouring.

After the concrete slab 14 is poured and hardens sufficiently, the sleeve screws 42 are progressively re-.

to roll out. Thereupon, the winged nuts 58 are retracted to expose the roller fixtures 48 to contact with the formwork beams 16 and with the pins 64 engaging the sides of the beams, the rollers 54 are held oriented in the roll out direction.

After roll out, the reverse order of assembly steps is taken. Parts can be inspected, repaired or replaced,

cleaned and oiled for repeated use on slabs for floors I above.

In event any contractor desires for any reason to handle the jack screw assembly and support as a bracket, the nut 38 need only be spot welded by bin to the upper end of the tube 26 and the sleeve screw is threadedly attached thereto but the many advantages and versatility is impaired.

Screws are generally the only parts that become damaged in use and may require attention that cannot be given while mounted in place, and heretofore the whole assembly generally has had to be removed because damage has occurred at its upper end. With the present invention, both bolts may be loosened and one removed. The support is then tilted to drop out the damaged screw assembly and replace it with another one and the support again quickly tilted back, tightened in place and the fixtures adjusted as to their appropriate heights.

What is claimed is:

1. In a device of the class described, the combination of a plurality of vertically oriented horizontally spaced work support tube means removably secured to vertical weight supporting members and having an upwardly directed weight bearing end located well above a work space on a floor,

jack means telescopically received in each support tube means including screws whose major radial dimension engage the respective tubes in telescopic rigid erecting relationship,

nut means engaging said screws and supported on said ends to cam the screws upwardly or downwardly predetermined distances in weight supported relationship on said ends when the screws are rotated,

roller fixtures rotatively supported on the upper ends of the screws to engage an object to be supported in rolling relationship,

head fixtures non-rotatively telescoping with the respective roller fixtures and rotatively mounted on the screws to engage a formwork member in supported rigid relationship,

a manually controlled nut on each screw above said nut means adjustably carrying the weight of each head fixture when raised above the level of the roller fixture, and

means for selectively rotating said screws to coordinate the height of said roller fixtures.

2. The combination defined in claim 1 in which said screws are sleeve screws having a coarse thread and open at the top, and said roller fixtures each including a spindle rotatively telescoping in said open top to rest on the upper end of the respective sleeve screws.

3. The combination defined in claim 1 in which said manually controlled nuts are winged nuts and said head means includes at least one upright element engaging the side of a formwork member resting on said roller fixture.

4. In a device of the class described for fixedly supporting and rolling two objects at different levels with respect to each other in'weight supported relation, one object of which is a support that has a tubular vertically oriented member, the improvement comprising,

jack screw means telescopically received rotatably in said tubular member for close axial alignment at one of its ends and having a heavy weight bearing thread intermediate its ends,

first nut means carried by the screw means in threaded relationship intermediate its ends for engaging the tubular means in screw supporting adjustable relation with respect thereto,

means interengaging said nut means and support to hold them against relative rotation,

a roller fixture rotatively supported upon the other end of said jack screw means to engage the other one of said objects,

a head fixture rotatively supported on said other end in telescoping relation with the roller fixture to rigidly engage said other one of said objects under weight bearing conditions when disposed above the level of said roller fixture,

second nut means carried by the screw means above the first nut means, and

means for rotating said screw means.

5. In a device of the class described for detachable mounting on a vertical member employed in supporting floor slab formwork, the combination of a support member having a base member with laterally spaced holes and vertically oriented tube means having an end spaced a predetermined distance above a work space on a floor, means for releasably supporting said base member to said vertical member at each of said holes, and a jack means freely received telescopically in said tube means in weight supported relationship, said jack means including a screw member telescopically received in said tube means having laterally extending thread elements spaced axially along its surface, which engage said tube means in rigid erecting relationship,

cam nut means received by the screw member intermediate its ends located in weight bearing relation against said end of the tubular means in heightadjusting relation to move the screw member upwardly and downwardly predetermined distances in supporting relation upon rotation of the screw member,

means interconnecting the cam nut means and support member against relative rotation in its weight 8 bearing position,

winged nut means on thescrew member above said cam nut means. head fixture means rotatively supported upon the upper end of said screw member to engage formwork and having a collar means resting against said winged nut means to move upwardly and downwardly upon rotation of the winged nut means,

roller fixture means rotatably carried by said screw member at the top thereof in telescoping relation with the head fixture means to engage formwork in roll out supported relation, and

wrenching means on said screw member for turning 6. The device defined in claim 5 in which said screw member is an externally threaded sleeve member and said roller fixture means includes a spindle received in the top end of the screw member with a roller support bracket to engage the upper end of the sleeve member in weight bearing relationship.

7. The device defined in claim 5 in which said head fixture means comprises a yoke defining a planar upper surface to engage the bottom of a formwork beam in supporting relation and upright members disposed on opposite sides to engage the sides of the formwork beam in non-rotatable relationship.

8. The device defined in claim 5 in which said head fixture means defines a horizontal surface to engage the bottom of a formwork beam, and upright elements to engage the sides of the formwork at least two of which are spaced from each other across the axis of screw rotation a distance substantially greater than the width of the beam with at least one of them taller than another one by a distance at least one-half the lead of the thread on the screw to engage the side of the beam to locate the roller crosswise of the beam when rotated and lifted by adjustment of the screw.

9. The device defined in claim 6 in which said collar means and spindle overlap each other and an upper end wall portion of said screw member in coaxial mutual strengthening relationship.

10. The device defined in claim 6 in which said wrenching means on said screw member comprises a wrench receiving element on the lower end of said sleeve member defining a drain passage from said sleeve member. 

1. In a device of the class described, the combination of a plurality of vertically oriented horizontally spaced work support tube means removably secured to vertical weight supporting members and having an upwardly directed weight bearing end located well above a work space on a floor, jack means telescopically received in each support tube means including screws whose major radial dimension engage the respective tubes in telescopic rigid erecting relationship, nut means engaging said screws and supported on said ends to cam the screws upwardly or downwardly predetermined distances in weight supported relationship on said ends whEn the screws are rotated, roller fixtures rotatively supported on the upper ends of the screws to engage an object to be supported in rolling relationship, head fixtures non-rotatively telescoping with the respective roller fixtures and rotatively mounted on the screws to engage a formwork member in supported rigid relationship, a manually controlled nut on each screw above said nut means adjustably carrying the weight of each head fixture when raised above the level of the roller fixture, and means for selectively rotating said screws to coordinate the height of said roller fixtures.
 2. The combination defined in claim 1 in which said screws are sleeve screws having a coarse thread and open at the top, and said roller fixtures each including a spindle rotatively telescoping in said open top to rest on the upper end of the respective sleeve screws.
 3. The combination defined in claim 1 in which said manually controlled nuts are winged nuts and said head means includes at least one upright element engaging the side of a formwork member resting on said roller fixture.
 4. In a device of the class described for fixedly supporting and rolling two objects at different levels with respect to each other in weight supported relation, one object of which is a support that has a tubular vertically oriented member, the improvement comprising, jack screw means telescopically received rotatably in said tubular member for close axial alignment at one of its ends and having a heavy weight bearing thread intermediate its ends, first nut means carried by the screw means in threaded relationship intermediate its ends for engaging the tubular means in screw supporting adjustable relation with respect thereto, means interengaging said nut means and support to hold them against relative rotation, a roller fixture rotatively supported upon the other end of said jack screw means to engage the other one of said objects, a head fixture rotatively supported on said other end in telescoping relation with the roller fixture to rigidly engage said other one of said objects under weight bearing conditions when disposed above the level of said roller fixture, second nut means carried by the screw means above the first nut means, and means for rotating said screw means.
 5. In a device of the class described for detachable mounting on a vertical member employed in supporting floor slab formwork, the combination of a support member having a base member with laterally spaced holes and vertically oriented tube means having an end spaced a predetermined distance above a work space on a floor, means for releasably supporting said base member to said vertical member at each of said holes, and a jack means freely received telescopically in said tube means in weight supported relationship, said jack means including a screw member telescopically received in said tube means having laterally extending thread elements spaced axially along its surface, which engage said tube means in rigid erecting relationship, cam nut means received by the screw member intermediate its ends located in weight bearing relation against said end of the tubular means in height-adjusting relation to move the screw member upwardly and downwardly predetermined distances in supporting relation upon rotation of the screw member, means interconnecting the cam nut means and support member against relative rotation in its weight bearing position, winged nut means on the screw member above said cam nut means, head fixture means rotatively supported upon the upper end of said screw member to engage formwork and having a collar means resting against said winged nut means to move upwardly and downwardly upon rotation of the winged nut means, roller fixture means rotatably carried by said screw member at the top thereof in telescoping relation with the head fixture means to engage formwork in roll out supported relation, and wrenching means on said screw membEr for turning it.
 6. The device defined in claim 5 in which said screw member is an externally threaded sleeve member and said roller fixture means includes a spindle received in the top end of the screw member with a roller support bracket to engage the upper end of the sleeve member in weight bearing relationship.
 7. The device defined in claim 5 in which said head fixture means comprises a yoke defining a planar upper surface to engage the bottom of a formwork beam in supporting relation and upright members disposed on opposite sides to engage the sides of the formwork beam in non-rotatable relationship.
 8. The device defined in claim 5 in which said head fixture means defines a horizontal surface to engage the bottom of a formwork beam, and upright elements to engage the sides of the formwork at least two of which are spaced from each other across the axis of screw rotation a distance substantially greater than the width of the beam with at least one of them taller than another one by a distance at least one-half the lead of the thread on the screw to engage the side of the beam to locate the roller crosswise of the beam when rotated and lifted by adjustment of the screw.
 9. The device defined in claim 6 in which said collar means and spindle overlap each other and an upper end wall portion of said screw member in coaxial mutual strengthening relationship.
 10. The device defined in claim 6 in which said wrenching means on said screw member comprises a wrench receiving element on the lower end of said sleeve member defining a drain passage from said sleeve member. 